Hard drive

The hen guardian's external hard drive died when she was on holiday a couple of weeks ago.  Fortunately, most of the contents were backed up elsewhere. There were a few photos missing, but not enough to be worth going to a recovery service.  So I opened it up, after having to order a 5-lobed screwdriver bit for the last screw, and followed the instructions I found in a YouTube video, but I wasn't able to get it going again.  (I have opened disks before, but I've never tried to access them afterwards.) They are amazing pieces of engineering.